SYSTEM, METHOD AND APPARATUS WITH MULTIPLE RESERVOIRS FOR IN SITU CALIBRATION OF IMPLANTABLE SENSORS

• US 20160058343A1
• Filed: 07/21/2015
• Published: 03/03/2016
• Est. Priority Date: 08/26/2014
• Status: Active Grant

• Current Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Original Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Inventors: Di Cristina, John F.
• Granted Patent: US 9,949,673 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes

Abstract

A subcutaneous sensor system includes a sensor, a plurality of reservoirs, a plurality of pumps, a mixer provided with a plurality of mixer inlets and a mixer outlet, and a controller having an input coupled to the sensor output and a plurality of control outputs coupled to the plurality of pumps and the mixer. In certain embodiments, the system further includes an enclosure for the reservoirs, the pumps, the mixer and the controller, e.g. in the form of a skin patch or in the form of an implantable enclosure. In certain embodiments, the sensor is external to the enclosure and implanted beneath the skin tissue.

Claims

1. A subcutaneous sensor system with multiple reservoirs for calibrating solutions comprising:

a sensor having a sensor output;

a plurality of reservoirs provided with a corresponding plurality of reservoir outlets;

a plurality of pumps provided with a corresponding plurality of pump inlets and a corresponding plurality of pump outlets, wherein the plurality of pump inlets are coupled to the plurality of reservoir outlets;

a mixer provided with a plurality of mixer inlets and a mixer outlet, wherein the plurality of mixer inlets are coupled to the plurality of pump outlets; and

a controller having an input coupled to the sensor output and a plurality of control outputs coupled to the plurality of pumps and the mixer.

2. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 1 further comprising an enclosure for the reservoirs, the pumps, the mixer and the controller.

3. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 2 wherein the enclosure comprises a skin patch.

4. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 2 wherein the enclosure is implanted beneath skin tissue.

5. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 2 wherein the sensor is external to the enclosure and is implanted beneath skin tissue.

6. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 1 wherein the controller comprises a microcontroller unit (MCU).

7. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 6 wherein the MCU includes digital memory.

8. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 6 wherein the controller further comprises a sensor analog front end (AFE) coupling the MCU to the sensor.

9. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 8 wherein the sensor is coupled to the AFE with a conductor.

10. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 9 wherein the conductor is at least partially enclosed within a tube connected to the mixer outlet.

11. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 6 wherein the controller further includes a data interface coupled to the MCU.

12. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 6 wherein the controller further includes an auto-calculation (Autocal) controller coupling the MCU to the plurality of pumps and to the mixer.

13. A subcutaneous sensor system with multiple reservoirs for calibration solutions as recited in claim 1 wherein a first reservoir of the plurality of reservoirs contains a first calibration solution and a second reservoir of the plurality of reservoirs contains a second calibration solution different from the first calibration solution.

14. A subcutaneous sensor system with multiple reservoirs for calibration solutions as recited in claim 13 wherein the first calibration solution is chosen to be proximate a first end of a linear operating region of the sensor and the second calibration solution is chosen to be proximate a second end of the linear operating region of the sensor.

15. A subcutaneous sensor system with multiple reservoirs for calibration solutions as recited in claim 14 wherein the first calibration solution and the second calibration solution can be mixed in the mixer to provide a third calibration solution that is intermediate to the first calibration solution and the second calibration solution.

16. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 13 further comprising a third reservoir for a cleaning solution.

17. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 1 wherein the mixer comprises a mixing valve.

18. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 17 wherein the mixer comprises a plurality of mixing valves.

19. A subcutaneous sensor system with multiple reservoirs for calibrating solutions as recited in claim 1 wherein the controller comprises an integrated circuit.

20. A method for operating a subcutaneous sensor system with multiple reservoirs for calibrating solutions comprising:

detecting the presence of calibration-triggering event with a microcontroller;

measuring an initial value from a subcutaneous sensor;

bathing the sensor with a first calibration solution having a different value than the initial value, the first calibration solution being provided from at least one of a plurality of reservoirs;

measuring a first calibration value from the sensor that is associated with the first calibration solution;

bathing the sensor with a second calibration solution having about the same value as the initial value, the second calibration solution being provided by at least one of the plurality of reservoirs;

calculating the gain (m) and offset (b) for the sensor, whereby the transfer function f(x) for the sensor comprises y=f(x)=mx+b; and

using the transfer function to measure a calibrated sensor value of the sensor.